Ti(IV) ion-imprinted polymer as a new selective sorbent for extraction and pre-concentration of trace amounts of titanium ions in different samples

ABSTRACT

In this paper, a novel, simple, selective and effective solid phase extraction method based on ion-imprinted polymer (IIP) technology and flame atomic absorption spectrometry (FAAS) for separation and pre-concentration of trace amounts of titanium (IV) ions was reportd?. It was obtained by precipitation polymerisation by using 2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one titanium (IV) complex abbrivated as Ti(IV)-(morin), as the template molecule. After polymerisation, leaching the polymer in HNO₃ (50% (v/v) solution caused formation cavities in the polymer. Characterisation studies of the ?Ti(IV)-imprinted polymer (Ti-IP) was performed by FT-IR, UV-Vis and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) techniques and then, the effective factors on extraction were optimised. A sensitive response to Ti(IV) within a concentration range between 0.01 and 4.0 μg mL^?1 was achieved under the optimum conditions. A total of 10.0 ng mL^?1 and 80.0 mg g^?1 were obtained as limit of detection (LOD, 3Sb/m) and maximum adsorption capacity, respectively. The relative standard deviation (RSD) for eight replicates detections of 0.2 μg mL^?1 of Ti(IV)? was found to be 2.8%. By this method, pre-concentration factor (PF) of 100 was obtained. Successfully applying this method in the water and standard samples, reasonable results were obtained for the extraction and pre-concentration of the titanium ions.     

A pre-concentration procedure employing a new imprinted polymer for the determination of copper in water

This work describes the development by response surface methodology (RSM) of a procedure for copper determination by inductively coupled plasma optical emission spectrometry (ICP OES) in water samples after extraction by copper imprinted polymer. Results of the two-level full factorial design (2⁴) based on an analysis of variance demonstrated that only the solution pH; amount of polymer and adsorption time were statistically significant. Optimal conditions for the extraction of copper samples were obtained by using Box-Behnken design. Solution pH; amount of polymer and adsorption time were regarded as factors in the optimisation study. The working conditions were 4.6, 0.03?g and 3.5?h, for solution pH, amount of polymer; and adsorption time, respectively. Under the optimised experimental conditions, the detection limit of the proposed method followed by ICP OES was found to be 0.8?µg?L^?1. The relative standard deviation (RSD) was found to less than 0.81%. The pre-concentration factor was 22.5. The accuracy of the optimised procedure was evaluated by analysis of certified reference material. The method was applied to the determination of copper in water samples.     

Separation,pre-concentration and determination of trace amounts of lead(II) ions in environmental samples using two functionalised nanoporous silica gels containing a dipyridyl sub-unit

In this study, two functionalised nanoporous silica gels containing dipyridyl sub-unit (SiL1 and SiL2) as selective solid-phase extraction materials for separation, pre-concentration and determination of trace levels of Pb(II) ions by inductively coupled plasma optical emission spectroscopy (ICP-OES) was investigated. The experimental parameters including pH, amounts and type of sorbent, sample volume, eluent type and interfering ions on the recovery of the target analytes were investigated, and the optimal experimental conditions were established. Under the optimised operating conditions with the SiL2 as sorbent, an enrichment factor of 300 was obtained. The detection limit based on three times standard deviations of the blanks was 150 ng L^–1. The proposed method was applied to the determination of lead in natural and wastewater samples with satisfactory results (recoveries greater than 96.5%, RSDs lower than 5.0%).     

Simultaneous determination of copper,mercury and lead by first-order derivative spectrophotometry using dithizone as reagent

A first-order derivative spectrophotometric method has been developed for the simultaneous determination of copper, mercury and lead at g/L levels using dithizone as reagent. The procedure involves the simultaneous extraction of these elements by dithizone in chloroform from weakly alkaline solutions. Linear calibration curves were obtained in the ranges 0.5–10 (Cu), 1–10 (Hg) and 1–10 (Pb) g present in 40 ml of aqueous phase with detection limits of 5 g/L (Cu) and 20 g/L (Hg and Pb). The R.S.D.s for 100 g/L of copper, mercury and lead were 2.5, 2.6 and 3.1% respectively, for 5 determinations. The method is applicable for the determination of copper and lead in marine sediment samples with good precision and accuracy.     

Application of polyurethane foam as a sorbent for trace metal pre-concentration — A review

The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteristics of PUF (polyether and polyester type) are discussed and an introduction to the characterization of these sorption processes using different types of isotherms is given. Separation and pre-concentration methods using unloaded and loaded PUF in batch and on-line procedures with continuous flow and flow injection systems are presented. Methods for the direct solid sampling analysis of the PUF after pre-concentration are discussed as well as approaches for speciation analysis. Thermodynamic proprieties of some extraction processes are evaluated and the interpretation of determined parameters, such as enthalpy, entropy and Gibbs free energy in light of the physico-chemical processes is explained.     

Immunoassay for the detection of lead ions in environmental water samples

A rapid, simple, and reliable competitive immunoassay was developed for measurement of lead ions Pb(II) in environmental samples. Avian antibodies were produced against Pb(II). Since lead ions are too small to elicit an immune response, the metal was coupled to protein carrier Bovine serum albumin (BSA) using a bifunctional chelator 1-(4-isothiocyanobenzyl) ethylenediamine N,N,N′,N′-tetra acetic acid (ITCBE). Poultry birds (layers) were immunised with this Pb(II)–ITCBE–BSA immunoconjugate and the avian antibodies (IgY) isolated from egg yolk recognised Pb(II)-ITCBE complexes as capture reagent and a Pb(II)–ITCBE conjugate of Alkaline phosphatase as an enzyme label. Antibody reaction was optimised for different concentrations of antigen and antibody dilutions. Cross reactivity with other metals were below 1% in competitive ELISA. The IC₅₀ value of this avian antibody was 0.19?µg?mL^?1. The detection range and the detection limit were 0.02–1000?µg?mL^?1and 0.2?µg?mL^?1, respectively.     

Determination of lead and cadmium in tap water and apple leaves after preconcentration on a new acetylacetone bonded polyurethane foam sorbent

The present work describes a rapid, cost-effective analytical procedure for the determination of lead and cadmium in environmental samples by off-line preconcentration with polyurethane foam (PUF) functionalised with acetylacetone by covalent coupling through the–N=N–group. The optimum pH ranges for quantitative uptake were 5–7, 6–7 for lead and cadmium, respectively. The kinetics of metal uptake by the new foam was found to be fast, reaching equilibrium in a few minutes. Metal ions were sorbed in the minicolumn, eluted with acid solutions and determined by flame atomic absorption spectrometer (FAAS). Under the optimum conditions, the preconcentration factors obtained were 288 for Cd and 224 for Pb. The limits of detection of the proposed procedure were 0.09 and 0.07 µg L^?1 for Pb and Cd, respectively. The relative standard deviation (RSD) was less than 10%. The accuracy of the method was estimated by using environmental samples that were spiked with Cd and Pb ions. The capacity of the acetylacetone bonded PUF (AA-BPUF) sorbent at optimum conditions has been found to be 4.5, 6.9 µmol g^?1 of sorbent for Pb and Cd, respectively.     

Graphene oxide-based two-dimensional molecular brush for efficient removal of lead and copper ions from water media

In this study, graphene oxide (GO)-based two-dimensional molecular brush was fabricated by grafting polyacrylamide onto GO nanosheets for efficient removal of Pb²⁺ and Cu²⁺ from water media. Owing to the rich oxygen and nitrogen functional groups in the composites, the synthetic GO two-dimensional molecular brush can get the maximum adsorption capacity of 268.4 mg/g for Pb²⁺ and 127.2 mg/g for Cu²⁺, respectively. Moreover, the interspaces between the stacked two-dimensional molecular brushes provide fast pathways for the diffusion of heavy metal ions. As a result, GO-based two-dimensional molecular brush can reach the adsorption equilibrium within 60 min. These results indicated that the synthetic GO-based two-dimensional molecular brush is a promising adsorbent to separate heavy metal ions from water media.     

对氨基苯亚甲基硫代若丹宁固相萃取分离光度法测定环境水和食品样品中的铅

合成了新试剂对氨基苯亚甲基硫代若丹宁(ABTR),并用红外光谱、核磁共振氢谱和元素分析鉴定其结构。研究了ABTR与铅的显色反应,在pH3.8的HAc NaAc缓冲介质中,吐温80存在下,ABTR与铅反应生成2∶1稳定络合物,该络合物可被WatersSep PakC18小柱固相萃取,小柱上富集的络合物用乙醇洗脱后富集倍数可达50倍,在乙醇介质中,λmax=545nm,体系摩尔吸光系数ε=1.09×105L·mol-1·cm-1。铅量在0.05～4.0μg/mL内符合比尔定律,本法可用于环境水和食品样品中铅的测定。     

Simultaneous voltammetric analysis of lead,copper and mercury ions by carbon paste electrode based on 1-(3-aminopropyl) imidazole modified polymer

In this study, a carbon paste electrode modified with a novel 1-(3-aminopropyl) imidazole functionalised crosslinked chlorosulfonated poly(styrene)-divinyl benzene polymer was used for selective and sensitive determination of the trace amounts of Pb²⁺, Cu²⁺ and Hg²⁺ ions by square wave anodic stripping voltammetry. The effect of some parameters such as paste composition, pH, preconcentration time, reduction potential and time, type of supporting electrolyte and potential scan rate on the determination of metal ions were investigated to find the optimal conditions. The effective open-circuit accumulation of the studied metal ions was succeeded only by the modification of the carbon paste electrode with functional polymer. For 6 min open-circuit preconcentration, the detection limit of Pb²⁺, Cu²⁺ and Hg²⁺ was found to be 5, 9 and 14 µgL^?1, respectively at 100 mVs^?1. The results confirmed that the lower concentration levels of these trace metal ions can be determined with the increase of preconcentration time and/or potential scan rate. Good detection limits and large dynamic concentration ranges were also obtained for their binary and ternary mixtures. The optimised method was successively applied to determine the concentration of Pb²⁺, Cu²⁺ ions in the tap water sample and Cu²⁺ ion in the waste water sample in the presence of possible interfering species (RSD<1%, recoveries 96–110% for 4 min preconcentration).     

Chemically modified silica gel for selective solid-phase extraction and preconcentration of heavy metal ions

This paper describes our research on the synthesis of the sorbent with chemically bonded ketoimine groups, and, furthermore, using this sorbent in the SPE technique to extract and preconcentrate trace amounts of metal ions in water samples. Surface characteristics of the sorbent were determined by elemental analysis, NMR spectra for the solid phases (²⁹Si CP MAS NMR), and analysis of pore size distribution of the sorbent and nitrogen adsorption-desorption. The newly proposed sorbent with ketoimine groups was applied for the extraction and preconcentration of trace amounts of Cu (II), Cr (III) and Zn (II) ions from the water from a lake, post-industrial water and purified water unburdened back to the lake. The determination of the transition-metal ions was performed on an emission spectroscope with inductively coupled plasma ICP-OES. For the batch method, the optimum pH range for Cu (II) and Cr (III) extraction was equal to 5, and Zn(II)–to 8. All the metal ions can be desorbed from SPE columns with 10?mL of 0.5?mol?HNO₃. The detection limits of the method were found to be 0.7?µg?L^?1 for Cu (II), 0.08?µg?L^?1 for Cr (III), and 0.2?µg?L^?1 for Zn (II), respectively.     

Simultaneous pre-concentration procedure for the determination of cadmium and lead in drinking water employing sequential multi-element flame atomic absorption spectrometry

In this paper is proposed a simultaneous pre-concentration procedure using cloud point extraction for the determination of cadmium and lead in drinking water employing sequential multi-element flame atomic absorption spectrometry. The ligand used is 2-(2-thiazolylazo)-p-cresol (TAC) and the micellar phase is obtained using non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation.The optimization step was performed using two-level factorial design and Doehlert design. A multiple response function was established in order to get experimental conditions for simultaneous extraction of cadmium and lead.The method allows the determination of cadmium and lead with detection limits of 0.077 μg L^− 1 and 1.05 μg L^− 1 respectively, precision expressed as relative standard deviation (RSD) of 1.5 and 3.3% (n = 10) for cadmium concentrations of 30 μg L^− 1 and 50 μg L^− 1, respectively, and RSD of 1.8% and 2.7% for lead concentrations of 30 μg L^− 1 and 50 μg L^− 1, respectively. The accuracy was confirmed by analysis of a certified reference material of natural water.This method was applied for the determination of cadmium and lead in drinking water samples collected in Jaguaquara City, Brazil. Tests of addition/recovery were also performed for some samples and results varied from 95 to 104% for cadmium and 96 to 107% for lead. The cadmium and lead concentrations found in these samples were always lower than the permissible maximum levels stipulated by Brazilian Health Organization.     

Novel modified carbon nanotubes as a selective sorbent for preconcentration and determination of trace copper ions in fruit samples

In this work, multiwalled carbon nanotubes were reacted with N‐[3‐(triet‐hoxysilyl)propyl]isonicotinamide to prepare pyridine‐functionalized carbon nanotubes. This novel sorbent was characterized by infrared spectroscopy, thermal and elemental analysis, and scanning electron microscopy. Functionalized carbon nanotubes were applied for the preconcentration and determination of copper ions using flame atomic absorption spectrometry. Various parameters such as sample pH, flow rate, eluent type and concentration, and its volume were optimized. Under optimal experimental conditions, the limit of detection, the relative standard deviation, and the recovery of the method were 0.65 ng/mL, 3.2% and 99.4%, respectively. After validating the method using standard reference materials, the new sorbent was applied for the extraction and determination of trace copper(II) ions in fruit samples.     

电感耦合等离子体原子发射光谱法测定铅锌选矿流程原尾矿中铅锌铜

用5mL氟化氢铵(50g/L)、10mL盐酸、5mL硝酸、5mL高氯酸分解0.1g样品,盐酸(3%,V/V)为测定介质,定容在250mL容量瓶中,直接用电感耦合等离子体原子发射光谱法测定铅锌选矿流程原尾矿中的铅、锌、铜3种元素。根据分析线的选择原则,结合待测元素的检测范围,选择无干扰、峰形对称、灵敏度适中的谱线Pb 220.353nm、Zn 213.856nm、Cu 324.754nm作为分析线。各元素的质量浓度在一定范围内与其发射强度呈线性,校准曲线的线性相关系数均大于0.999 9,方法中各元素检出限为0.066～0.51ng/mL。方法经国家标准物质分析验证,测定值与认定值相符。按照实验方法测定铅锌选矿流程原尾矿中铅、锌、铜,测试结果与火焰原子吸收光谱法测定结果一致。     

A selective modified nanoporous silica as sorbent for separation and preconcentration of dysprosium in water samples prior to ICP-OES determination

In this research a new physically functionalized nanoporous silica (SBA-15) using N′-[(2-hydroxy phenyl) methylene] benzohydrazide (BBH) was utilized as a selective sorbent for the separation, preconcentration and determination of dysprosium (Dy) in natural water by inductively coupled plasma optical emission spectrometry (ICP-OES). The selectivity of BBH to Dy (III) ion was previously tested by conductometric and spectroscopic methods. Conditions for effective adsorption of Dy were optimized with respect to experimental parameters in batch process. The extraction recovery was 96.5, analytical curve was linear in the range 0.2–1000?µgL^?1, and the detection limit was 0.05?ng?mL^?1. The relative standard deviation (RSD) under optimal conditions was 3.2% (n?=?10). The sorbent exhibited high adsorption capacity and fast rate of equilibrium for sorption of Dy ions. The method was applied for recovery and determination of dysprosium in different environmental water samples.     

Determination of trace amounts of cadmium and copper by atomic absorption spectrometry after simultaneous extraction and preconcentration using a new water-soluble polyacrylic acid/alumina sorbent

An analytical method using alumina modified with water-soluble polyacrylic acid polymer for the simultaneous separation and preconcentration of trace Cu and Cd in a column system, and their determination by flame atomic absorption spectrometry was developed. The conditions for coating Al₂O₃ with polyacrylic acid were optimized, then the column was packed with 50 mg of this sorbent. Cd and Cu solution was passed through a glass column at pH 4.5, and elution was carried out with 5 mL of 0.05 M HCl at a flow rate of 1 mL min⁻¹. A sorption capacity of 10 mg Cu and 12 mg Cd was obtained for 1 g sorbent. The detection limit was calculated as 4.5 μg L⁻¹ for Cu and 1.54 μg L⁻¹ for Cd in the final solution. Enrichment factors of 300 for Cd and 400 for Cu were obtained.     

Highly efficient removal of toxic lead ions from aqueous solutions using a new magnetic metal‐organic framework nanocomposite

A magnetic metal‐organic framework (MOF) nanocomposite was successfully prepared by a new and green strategy through reasonable design. Magnetic MOF of Fe₃O₄‐NHSO₃H@HKUST‐1 nanocomposite use for removal of lead ions as an environmental pollutant. The experimental results indicated that the nano adsorbent of Fe₃O₄‐NHSO₃H@HKUST‐1 can removed lead ions under optimum operational conditions. The dosage of the nanocomposite, pH of the sample solution, and contact time were obtained to be 10 mg, 7.0, and 90 min, respectively, while the initial concentration of Pb(II) ions of 400 mg/L was used. A kinetic study indicated that a pseudo‐second‐order model agreed well with the experimental data. The isotherm experiments revealed that the Langmuir model attained better fits to the equilibrium data than the Freundlich model. The maximum adsorption capacity of the adsorbent for the removal of lead under the optimum operational conditions of pH 7.0 and temperature 25°C was found to be 384.6 mg/g. The thermodynamic parameters indicate that the adsorption of lead is spontaneous and endothermic. The magnetic MOF nanocomposite could be recovered easily and reused many times without significant loss of its nano‐adsorbent activity. The proposed method is simple, eco‐friendly, low cost, and efficient in the removal of lead ions from aqueous solutions.     

A pipette tip multiwalled-carbon nanotube solid-phase extraction of lead in water and hair samples: application of the statistical Taguchi method to optimise the experimental variables

A pipette tip multiwalled-carbon nanotube solid-phase extraction (PT-MWCNTs-SPE) coupled with flame atomic absorption spectrometry (FAAS) was developed for extraction and determination of lead in hair samples. In this study, PT-MWCNTs-SPE cartridge, assembled by packing MWCNTs as a sorbent into a 100-μL pipette tip. Taguchi’s method (L9 orthogonal array (OA)) as a statistical design of experiments was employed to optimise the factors and experiments that affected on the recovery of Pb(II). Under the optimum conditions, four parameters such as pH (P), volume of ligand (AL), sorbent amount (SA) and eluent concentrations of HNO₃ (EC) were chosen as important affecting parameters. The limit of detection (LOD) of this method was 0.86 µg L^?1 with relative standard deviations (RSD) ≤3% for Pb(II). Afterwards, the accuracy of proposed method was evaluated by TMDA 53.3 fortified water and NCS ZC 81002b human hair certified reference materials. The procedure was applied to lead contents of water and hair samples.     

Antibacterial,DFT and molecular docking studies of metformin complex as active material for the fabrication of copper (II) selective potentiometric sensor

The prepared and characterized metformin ‐copper (II) complex was used as elecroactive material for modification of a new sensitive and selective modified carbon paste electrode (MCPE) for the potentiometric determination of copper (II) in water samples. The performance characteristics of MCPE were carried out. The electrode showed perfect potentiometric response for Cu (II) over concentration range of 1.0 × 10^?6 – 5.0 × 10^?2 mol L^?1 with a detection limit of 1.0 × 10^?6 mol L^?1 with divalent slope value 30.8 ± 0.92 mV decade^?1 over the pH range of 2–6 and exhibits fast response time of 9 s. Also, this electrode exhibited good selectivity towards Cu (II) ions with respect to other metal ions. The obtained results using the proposed electrode were in a good agreement with those obtained using the inductively coupled plasma (ICP) method.     

Chemically functionalized silica nanoparticles‐based solid‐phase extraction for effective pre‐concentration of highly toxic metal ions from food and water samples

In this research study, an efficient solid‐phase extraction procedure based on a new organometallic, effective, eco‐friendly and bio‐degradable nanoadsorbent was firstly introduced for influential pre‐concentration of Cu(II), Zn(II), Pb(II), Cd(II) and Mn(II) ions from food and water samples followed by flame atomic absorption spectrophotometric determination. This safe adsorbent consisted of silica nanoparticles chemically functionalized with di‐ethylen tri‐amine (SiO₂@NH₂NPs); easily prepared via an effective and simple approach. Characterization of SiO₂@NH₂NPs was subsequently implemented via SEM, FT‐IR and XRD; certifying high quality of the modified nanoadsorbent in terms of size, shape and surface functional groups. The effects of the main factors on the extraction efficiency were then optimized. Efficient extraction of the analytes of interest at neutral media accompanied with the aid of a bio‐compatible organometallic nanoadsorbent can be considered as valuable advantages of the proposed approach. In the optimum conditions, calibration graphs were linear in the range of 4–700 μg l^?1, with higher correlation coefficients than 0.997 and limits of detection of 1.45–4.10 ng ml^?1. The enrichment factor values were found to be in the span of 120–400. The resultant extraction recovery values were satisfactory; possessing the proper relative standard deviation (%, n  =  5) values of 2.05–4.28%.